Illuminating optical system and color image projecting device

ABSTRACT

Decreasing the number of components and assembly processes for improving assembly efficiency and reducing production cost is promoted. A color image projecting device  31  comprises an illuminating optical system  32  and a projection optical system  33.  The illuminating optical system  32  comprises a light source emitting white light including red, green, and blue colors, a dividing-spectra block  35  having reflecting surface  35 A and  35 B reflecting the red and blue colors in three colors of light from the light source toward left and right while transmitting a green color of light, a red block  36  having a dichroic mirror  36 A provided in contact with the dividing-spectra block  35  and reflecting a red color of light reflected off the reflecting surface  35 A toward the projection optical system  33,  a blue color block  38  having a dichroic mirror  38 A like the red block  36,  and a green block  37  having a dichroic mirror  37 A reflecting a transmitted green color of light toward the projection optical system  33.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an illuminating optical system for dispersing white light into red, green, and blue colors of light and a color image projecting device for projecting a color image onto a screen and so forth using each color of light from the illuminating optical system.

[0002] Color image projecting devices are generally known which disperse white light, next transmit each dispersed light through picture elements, and then integrates each dispersed light into one in order to project it onto the screen and so forth. FIG. 2 shows one example of prior art color image projecting devices.

[0003] A color image projecting device 1 comprises a light source 2, an illuminating optical system 3, and a projection optical system 4.

[0004] The light source 2 comprises a lump 5 that emits the white light, two integrators 6 and 7, a PS conversion element 8 being provided between each of an integrator 6 and 7. The white light that is polarized to P polarized light and S polarized light is outputted from the light source 2.

[0005] The illuminating optical system 3 comprises a total reflection mirror 11, a first dichroic mirror 12, a second dichroic mirror 13, a third dichroic mirror 14, and relay lenses 15, 16, and 17. Each of mirrors and lenses is precisely positioned on an optical path. The total reflection mirror 11 total reflects the white light from the light source 2 toward the first dichroic mirror 12. The first dichroic mirror 12 transmits only a red color of light while reflecting the remaining green and blue colors of light. The second dichroic mirror 13 transmits only a blue color of light in the blue and green colors of light that are reflected off the first dichroic mirror 12 while reflecting a remaining green color of light. The third dichroic mirror 14 reflects the red color of light transmitted through the first dichroic mirror 12. Each relay lens 15, 16, and 17 adjusts each optical path of the red, green, and blue colors of light separated by each dichiroic mirror 13 and 14, whereby each light is incident on each of a red block 18, a green block 19, and a blue block 20 as described below.

[0006] The projection optical system 4 comprises the red block 18, the green block 19, the blue block 20, a condensing block 21, and a projection lens 22. The red block 18 forms a red projection image with the red color of light separated by the illuminating optical system 3. The green block 19 forms a green projection image with the green color of light separated by the illuminating optical system 3. The blue block 20 forms a blue projection image with the blue color of light separated by the illuminating optical system 3. The condensing block 21 integrates each projection image formed by the red block 18, the green block 19, and the blue block 20 into one projection image. The projection lens 22 projects the projection image integrated by the condensing block 21 onto the screen and so forth.

[0007] However, in the color image projecting device 1 comprised above, each mirror 11, 12, 13, and 14 and each lens 15, 16, and 17 is discrete components and requires increased number of components. Furthermore, positioning these components precisely on the optical path causes complex assembly processes and increased assembly processes. This results in problems such as increased production cost.

SUMMARY OF THE INVENTION

[0008] The present invention is in consideration of the above problems and the object of the invention is to provide an illuminating optical system and a color image projecting device to improve assembly efficiency for promoting production cost reduction by reducing the number of components and assembly processes.

[0009] In order to solve above problems, an illuminating optical system of a first invention comprises a light source that emits white light including red, green, and blue colors and a dividing-spectra block that is provided facing the light source, said dividing-spectra block having at least a first reflecting surface that is provided on an optical path from said light source and reflects one of three colors of light while transmitting remaining colors of light, a first reflecting surface for extraction that extracts light reflected off the first reflecting surface by reflection in a predetermined direction, a second reflecting surface that is provided on the optical path from said light source and reflects another one of said three colors of light while transmitting a remaining color of light, and a second reflecting surface for extraction that extracts light reflected off the second reflecting surface by reflection in a predetermined direction.

[0010] In accordance with the above-described configuration, the first reflecting surface of the dividing-spectra block directs one of the three colors of light toward the first reflecting surface for extraction by reflection. The first reflecting surface for extraction extracts the light from the first reflecting surface by reflection in the predetermined direction. The second reflecting surface directs one of the remaining two colors of light other than the one of the three colors of light already extracted by reflection with the first reflecting surface toward the second reflecting surface for extraction by reflection while transmitting the remaining one color of light. The second reflecting surface for extraction extracts light from the second reflecting surface by reflection in the predetermined direction. The light that is not reflected off the first and the second reflecting surfaces but is transmitted through them is directly extracted in the predetermined direction or extracted in the predetermined direction by providing a third reflecting surface for extraction. Therefore, the three colors of light from the white light are extracted by separating them in the predetermined direction.

[0011] An illuminating optical system of a second invention comprises a light source that emits white light including red, green, and blue colors, a first block that has at least a reflecting surface which reflects or transmits one of three colors of light from the light source in a predetermined direction while transmitting or reflecting remaining colors of light, and a second block that is provided in contact with the first block and has at least a reflecting surface which reflects or transmits one of two colors of light transmitted through or reflected off said reflecting surface in a predetermined direction while transmitting or reflecting a remaining color of light.

[0012] In accordance with the above-described configuration, the white light outputted from the light source is inputted to the first block, whereby one of the red, green, and blue colors of light in the three colors of light is extracted by being reflected off or transmitted through in the predetermined direction. The remaining colors of light are inputted to the second block in contact with the first block. In the second block, one of the inputted two colors of light is extracted by reflection or transmission in the predetermined direction while the remaining color of light is extracted by transmission or reflection in the predetermined direction. Therefore, the three colors of light are extracted by separating them in the predetermined direction.

[0013] The illuminating optical system of said second invention is preferably provided with a third block that is provided in contact with said second block and has a reflecting surface which reflects light transmitted through or reflected off the reflecting surface of the second block in a predetermined direction.

[0014] In accordance with the above-described configuration, the first block extracts one of the three colors of light included in the white light emitted from the light source in the predetermined direction and the second block extracts one of the two colors of light in the predetermined direction. And, the remaining color of light is inputted to the third block in contact with the second block. The third block extracts the light inputted from the second block by reflection with the reflecting surface of the third block in the predetermined direction. Therefore, the three colors of light are extracted by separating them in the predetermined direction.

[0015] An illuminating optical system of a third invention comprises a light source that emits white light including red, green and blue colors, a dividing-spectra block in which a first reflecting surface that reflects one of three colors of light from the light source while transmitting remaining colors of light and a second reflecting surface that reflects another color of light while transmitting a remaining color of light are provided on an identical optical path in order to disperse said three colors of light in three directions, a red block that is provided in contact with a surface of the dividing-spectra block from which a red color of light is outputted and has a reflecting surface for extraction which extracts the red color of light by reflection in a predetermined direction, a green block that is provided in contact with a surface of said dividing-spectra block from which a green color of light is outputted and has a reflecting surface for extraction which extracts the green color of light by reflection in a predetermined direction, and a blue block that is provided in contact with a surface of the dividing-spectra block from which a blue color of light is outputted and has a reflecting surface for extraction which extracts the blue color of light by reflection in a predetermined direction.

[0016] In accordance with the above-described configuration, the white light emitted from the light source is inputted to the dividing-spectra block. In the dividing-spectra block, one of the three colors of light included in the white light is reflected off the first reflecting surface. One of the remaining two colors of light is reflected off the second reflecting surface. The remaining one color of light is transmitted through the first and the second reflecting surfaces. The red block being provided in contact with the surface of the dividing-spectra block from which the red color of light is outputted extracts the inputted red color of light by reflection in the predetermined direction with the reflecting surface for extraction. The green block being provided in contact with the surface of the dividing-spectra block from which the green color of light is outputted extracts the inputted green color of light by reflection in the predetermined direction with the reflecting surface for extraction. The blue block being provided in contact with the surface of the dividing-spectra block from which the blue color of light is outputted extracts the inputted blue light by reflection in the predetermined direction with the reflecting surface for extraction. Therefore, said three colors of light are extracted by dispersion in the predetermined direction.

[0017] The illuminating optical system of each of said inventions is characterized in that said each reflecting surface of said each block comprises a dichroic mirror which reflects or transmits only any one of said red, green, and blue colors of light.

[0018] In accordance with the above-described configuration, only one of three colors of light can be reliably extracted by reflection with the dichroic mirror.

[0019] The illuminating optical system of each of said inventions is characterized in that said each block is formed of transparent plastic.

[0020] In accordance with the above-described configuration, easy and precise assembly of the illuminating optical system without requiring fine adjustment of an optical axis to each reflecting surface can be achieved by forming each block with transparent plastic and by adhering one to the other.

[0021] A color image projecting device of a fourth invention in which an illuminating optical system that outputs red, green, and blue colors by separating the white light and a projection optical system that forms a color projection image by said three colors of light from the illuminating optical system are provided, said color image projecting device employs any of said illuminating optical systems as said illuminating optical system.

[0022] In accordance with the above-described configuration, easy assembly is accomplished without fine adjustment to the optical axis by simply adhering one to the other. Moreover, this reduces production cost as well as the number of components and assembly processes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 shows an exploded perspective view of a color image projecting device of a first embodiment.

[0024]FIG. 2 shows a schematic view of prior art color image projecting device.

[0025]FIG. 3 shows an exploded perspective view of the color image projecting device of a second embodiment.

[0026]FIG. 4 shows a perspective view of an illuminating optical system of the color image projecting device of a first modification.

[0027]FIG. 5 shows a perspective view of the illuminating optical system of the color image projecting device of a second modification.

[0028]FIG. 6 shows a perspective view of the illuminating optical system of the color image projecting device of a third modification.

[0029]FIG. 7 shows a perspective view of the illuminating optical system of the color image projecting device of a fourth modification.

BEST MODE OF THE PREFERRED EMBODIMENT

[0030] Hereinafter, preferred embodiments of an illuminating optical system and a color image projecting device of the present invention are described with reference to the drawings.

[0031] First, the color image projecting device of a first embodiment will be described. FIG. 1 shows an exploded perspective view of the color image projecting device of the embodiment.

[0032] A color image projecting device 31 of the embodiment comprises a light source (not shown), an illuminating optical system 32, and a projection optical system 33.

[0033] As well as said prior art light source 2, the light source outputs white light in which red, green, and blue colors of light are included. The white light from the light source is inputted to the illuminating optical system 32.

[0034] The illuminating optical system 32 comprises a dividing-spectra block 35, a red block 36, a green block 37, and a blue block 38.

[0035] The dividing-spectra block 35 is a block for extracting three colors of light, namely the red, green, and blue colors of light from the white light by dispersion. The dividing-spectra block 35 is formed in the shape of a regular hexahedron with transparent synthetic resins such as olefin, acrylic, and polycarbonate. Two reflecting surfaces 35A and 35B are provided in the dividing-spectra block 35. Each reflecting surface 35A and 35B is provided vertically in the shape so that both surfaces intersect at right angles with each other along diagonal lines. The first reflecting surface 35A comprises a dichroic mirror which reflects a red color of light included in the inputted white light in the orthogonal direction against an optical path S while transmitting the remaining colors of light. The second reflecting surface 35B comprises a dichroic mirror which reflects a blue color of light included in the white light in the orthogonal direction against the optical path S and yet in the opposite direction to said red color of light while transmitting a remaining color of light. Therefore, the red color of light included in the white light which is incident on along the optical path S is configured to be reflected in the orthogonal direction by the first reflecting surface 35A, the blue color of light is configured to be reflected in the opposite direction to the red color of light by the second reflecting surface 35B, and a green color of light is configured to be transmitted through the dividing-spectra block 35, whereby three colors of light are dispersed in three directions.

[0036] The red block 36 is a block for outputting the red color of light to the projection optical system 33. The red block 36 is formed in the shape of a triangular prism with transparent synthetic resins such as olefin, acrylic, and polycarbonate. More specifically, the red block 36 is formed in the shape of the triangular prism obtained by dividing the regular hexahedron into halves along a diagonal line. A dichroic mirror 36A for reflecting the red color of light is provided on an inclined surface of the red block 36 formed in the shape of the triangular prism and is configured to reflect the red color of light from the dividing-spectra block 35 in a projecting direction T. The dichroic mirror 36A may be formed directly on the inclined surface of the red block 36 by deposition or adhered thereto as a plate. Note that a refractive index of an interface is kept in mind when the plate is adhered. In addition, a total reflection mirror formed by aluminum deposition and so forth may be provided on the inclined surface of the red block 36 because the first reflecting surface 35A of the dividing-spectra block 35 extracts only the red color of light. The red block 36 is integrally adhered to an output surface of the red color of light of the dividing-spectra block 35.

[0037] The green block 37 is a block for outputting the green color of light to the projection optical system 33. The green block 37, as well as said red block 36, is formed in the shape of the triangular prism with transparent synthetic resins such as olefin, acrylic, and polycarbonate. A dichroic mirror 37A for reflecting the green color of light is provided on an inclined surface of the green block 37 formed in the shape of the triangular prism and is configured to reflect the green color of light included in the light from the dividing-spectra block 35 in the projecting direction T. In the dividing-spectra block 35, the light which is transmitted through the first reflecting surface 35A and the second reflecting surface 35B is inputted to the green block 37 and the dichroic mirror 37A is used because the light in which the red and blue colors of light are not included may still include light other than the green color of light. The dichroic mirror 37A may be formed by deposition or adhered as the plate. Note that the refractive index of the interface must be kept in mind when the plate is adhered. The green block 37 is integrally adhered to an output surface of the green color of light of the dividing-spectra block 35.

[0038] The blue block 38 is a block for outputting the blue color of light to the projection optical system 33. The blue block 38, as well as said red color block 36, is formed in the shape of the triangular prism with transparent synthetic resins such as olefin, acrylic, and polycarbonate. A dichroic mirror 38A for reflecting the blue color of light is provided on an inclined surface of the blue color block 38 formed in the shape of the triangular prism and is configured to reflect the blue color of light from the dividing-spectra block 35 in the projecting direction T. The dichroic mirror 38A may be formed by deposition or adhered as the plate. Note that the refractive index of the interface must be kept in mind when the plate is adhered. In addition, the total reflection mirror formed by aluminum deposition and so forth may be provided on the inclined surface of the blue block 38 because the second reflecting surface 35B of the dividing-spectra block 35 extracts only the blue color of light. The blue block 38 is integrally adhered to an output surface of the blue color of light of the dividing-spectra block 35.

[0039] The projection optical system 33 comprises a red projection block 41, a green projection block 42, a blue projection block 43, a condensing block 44, and a projection lens 45 (Refer to FIG. 3).

[0040] The red projection block 41 is a block for producing a red projection image with the red color of light. The red projection block 41 is adhered to an output surface of the red color of light of the red block 36 in the illuminating optical system 32. The red projection block 41 is formed in the shape of the regular hexahedron, and a PBS plate 47 and a red panel 48 are provided therein. PBS plate 47 is provided in the red projection block 41. More specifically, the PBS plate 47 is provided along a diagonal line of the red projection block 41 having the shape of the regular hexahedron and is inclined outwardly at an angle of 45 degrees against an optical path of outputted light from the red block 36. Either of P polarized light or S polarized light is transmitted through the PBS plate 47 while the other is reflected. Therefore, the red color of light inputted from the red block 36 in the illuminating optical system 32 is configured to be reflected, so that it is guided to the red panel 48 while the red color of light, whose plane of polarization is rotated by 90 degrees, from the red panel 48 is configured to be transmitted, so that it is outputted to the condensing block 44. The red panel 48 is provided with red picture elements such as liquid crystal for producing an image by selectively reflecting the red color of light. In addition, a function is provided that rotates the plane of polarization of the red light reflected off the PBS plate 48 by 90 degrees. The red panel 48 is attached to an outer end face of the red projection block 41.

[0041] The green projection block 42 is a block for producing a green projection image with the green color of light. The green projection block 42 is adhered to an output surface of the green color of light of the green block 37 in the illuminating optical system 32. The green projection block is formed in the shape of the regular hexahedron, and a PBS plate 49 and a green panel 50 are provided therein. A PBS plate 49, as well as said PBS plate 47, is configured to reflect the green color of light from the green block 37 in the illuminating optical system 32, so that it is guided to the green panel 50 while being configured to transmit the green color of light, whose plane of polarization is rotated by 90 degrees, from the green panel 50, so that it is outputted to the condensing block 44. The green panel 50 is provided with green picture elements such as liquid crystal for producing an image by selectively reflecting the green color of light. In addition, a function is provided that rotates the plane of polarization of the red color of light reflected off the PBS plate 49 by 90 degrees. The green panel 50 is attached to an outer end face of the green projection block 42.

[0042] The blue projection block 43 is a block for producing a blue projection image with the blue color of light. The blue projection block 43 is adhered to an output surface of the blue color of light of the blue block 38 in the illuminating optical system 32. The blue projection block 43 is formed in the shape of the regular hexahedron, and a PBS plate 51 and a blue color panel 52 are provided therein. The PBS plate 51, as well as said PBS plate 47, is configured to reflect the blue color of light from the blue block 38 in the illuminating optical system 32, so that it is guided to the blue panel 52 while being configured to transmit the blue color of light, whose plane of polarization is rotated by 90 degrees, from the blue panel 52, so that it is outputted to the condensing block 44. The blue panel 52 is provided with blue color picture elements for producing an image by selectively reflecting the blue color of light. In addition, a function is provided that rotates the plane of polarization of the red color of light reflected off the PBS plate 51 by 90 degrees. The blue panel 52 is attached to an outer end face of the blue color projection block 43.

[0043] The condensing block 44 is a block for integrating the red color of light from the red projection block 41, the green color of light from the green projection block 42, and the blue color of light from the blue projection block 43. Two reflecting plates 55 and 56 are provided vertically in the shape so that both plates intersect at right angles with each other along diagonal lines within the condensing block 44. A first reflecting plate 55 reflects red color of light inputted from the red projection block 41 toward a projection lens 45 while transmitting the other colors of light. A second reflecting plate 56 reflects blue color of light inputted from the blue projection block 43 toward the projection lens 45 while transmitting the other colors of light. In addition, each of the reflecting plates 55 and 56 transmits the green color of light inputted from the green projection block 42 toward the projection lens 45 without reflecting it. Therefore, three colors of light are configured for being integrated by the condensing block 44 so as to be outputted to the projection lens 45.

[0044] In the condensing block 44, the red projection block 41 is adhered to an input surface of the red color of light, the green projection block 42 is adhered to an input surface of the green color of light, and the blue projection block 43 is adhered to an input surface of the blue color of light. In addition, the condensing block 44 is also adhered to the dividing-spectra block 35 of the illuminating optical system 32.

[0045] The projection lens 45 is a lens for projecting light outputted from the condensing block 44 to a projection object such as screen and so forth. The projection lens 45 is provided facing an output surface of the condensing block 44.

[0046] The illuminating optical system 32 of the color image projecting device 31 as comprised above is assembled in the following manner. The red block 36, the green block 37, and the blue block 38 are respectively adhered to the dividing-spectra block 35 consistently. Moreover, in the projection optical system 33, the red projection block 41, the green projection block 42, and the blue projection block 43 are respectively adhered to the condensing block 44 consistently. Then, the dividing-spectra block 35, the red block 36, the green block 37, and the blue block 38 of the illuminating optical system 32 are respectively adhered to the condensing block 44, the red projection block 41, the green projection block 42, and the blue projection block 43 of the projection optical system 33, whereby an entire unit is assembled.

[0047] In the color image projecting device 31 assembled like above-described manner, the white light from the light source is separated by the dividing-spectra block 35 into the three colors of light (red, green, and blue) to be inputted to the red block 36, the green block 37, and the blue block 38. Then, the dichroic mirrors 36A, 37A, and 38A of the red block 36, the green block 37, and the blue block 38 reflect each color of light being incident on the projection optical system 33.

[0048] In the projection optical system 33, each of the red, green, and blue color of light from each of the red block 36, the green block 37, and the blue block 38 of the illuminating optical system 32 is inputted to the red projection block 41, the green projection block 42, and the blue projection block 43, whereby each projection image is formed and then each of the images is inputted to the condensing block 44 to be integrated and projected via the projection lens 45 on the screen and so forth.

[0049] Reduction of the number of components and assembly processes can be achieved because the illuminating optical system 32 and the projection optical system 33 are produced per each block and the entire unit is assembled simply by consistently adhering one to the other as described above.

[0050] Since positioning or fine adjusting of respective components onto an optical axis is not necessary, assembly of the color image projecting device 31 is performed very easy and assembly efficiency is greatly improved. Furthermore, this decreases the number of components and reduces production cost.

[0051] Next, a second embodiment of the present invention is described according to FIG. 3. Since the projection optical system of the color image projecting device of the embodiment comprises the same configuration as that of the projection optical system 33 of the color image projection system 31 of said first embodiment, identical numbers are assigned to identical portions for abbreviating description. The embodiment is characterized by an illuminating optical system 60. In addition, a light source 61 comprises a lamp 62, an integrator 63, and an IR cut filter 64.

[0052] The illuminating optical system 60 of the embodiment comprises a first block 66, a second block 67, and a third block 68.

[0053] The first block 66 is a block for reflecting one of said three colors of light in a predetermined direction while transmitting the remaining colors of light. The first block 66 comprises two triangular prisms, each of said prisms is obtained by dividing the regular hexahedron into halves along a diagonal line, each of which is turned by 90 degrees one another and is united with each other. A first inclined surface 66A on the side of the light source 61 is facing upward and a second inclined surface 66B on the opposite side is facing sideways. The first inclined surface 66A is configured to be a reflecting surface. A dichroic mirror 71 is adhered to the first inclined surface 66A for reflecting the red color of light as shown in graph of FIG. 3. In addition, the dichroic mirror 71 may be formed on the first inclined surface 66A by deposition. The dichroic mirror 71 reflects the red color of light upward while transmitting the remaining colors of light. The red color of light reflected off the first inclined surface 66A is inputted to the red projection block 41 of the projection optical system 33. The second inclined surface 66B is united with a first inclined surface 67A of the second block 67 to form a reflecting surface. A vertical surface 66C opposing to the second inclined surface 66B is configured to be an output surface of the green color of light that is reflected off the second inclined surface 66B (the first inclined surface 67A).

[0054] The second block 67 is a block for reflecting one of the remaining two colors of light other than the red color of light from the first block 66 in a predetermined direction while transmitting the remaining one color of light in a predetermined direction. As well as said first block 66, the second block 67 comprises two triangular prisms, each of said prisms is obtained by dividing the regular hexahedron into halves along the diagonal line, each of which is turned by 90 degrees one another and is united with each other. In addition, a triangular prism provided in contact with the first block 66 is formed slightly smaller than the other triangular prism here. This is because thickness of a diachronic mirror 72 described later is kept in mind. The first inclined surface 67A on the side of the first block 66 is facing sideways and a second inclined surface 67B on the opposite side is facing downward. The first inclined surface 67A is configured to be a reflecting surface. The dichroic mirror 72 is adhered to the first inclined surface 67A for reflecting the green color of light as shown in graph of FIG. 3. In addition, the dichroic mirror 72 may be formed on the first inclined surface 67A by deposition. The dichroic mirror 72 reflects the green color of light sideways while transmitting the remaining color of light. Although the red color of light can also be reflected off, only the green color of light is reflected because the red color of light is already removed by said dichroic mirror 71. The second inclined surface 67B is configured to be a reflecting surface for reflecting the blue color of light. When the light that is inputted to the second inclined surface 67B is only the blue color of light, a total reflection mirror formed by aluminum deposition and so on are provided. When the light other than the blue color of light is included, a dichroic mirror for reflecting the blue color of light is provided. A horizontal surface 67C opposing to the second inclined surface 67B is configured to be an output surface of the blue color of light reflected off the second inclined surface 67B. The blue color of light outputted from the horizontal surface 67C is inputted to the blue projection block 43 of the projection optical system 33.

[0055] The third block 68 is a block for reflecting the green color of light reflected off the second inclined surface 66B of the first block 66 (the first inclined surface 67A of the second block 67) and is outputted from the vertical surface 66C in a predetermined direction. The third block 68 is formed in the shape of two triangular prisms each of which is obtained by dividing the regular hexahedron into halves along the diagonal line. A total reflection mirror is provided on an inclined surface 68A of the third block 68. A dichroic mirror that reflects the green color of light may be available instead of the total reflection mirror. A horizontal surface 68B opposing to the inclined surface 68A is configured to be an output surface of the green color of light reflected off the inclined surface 68A. The green color of light outputted from horizontal surface 68B is inputted to the green projection block 42 of the projection optical system 33.

[0056] In the illuminating optical system 60 of the color image projecting device as comprised above, the first block 66, the second block 67, the third block 68, and the dichroic mirrors 71 and 72 are respectively adhered to one another. Then, the horizontal surface 67C of the second block 67 is adhered to the blue projection block 43 of the projection optical system 33 and the horizontal surface 68B of the third block 68 is adhered to the green color projection block 42 of the projection optical system 33, whereby an entire unit is assembled.

[0057] And, in the illuminating optical system 60, the white light from the light source is separated into three colors of light (red, green, and blue color of light) by the dichroic mirrors 71 and 72 and so forth to be inputted to the projection optical system 33.

[0058] In the projection optical system 33, the projection image is projected on the screen and so forth as is the case with the action of the first embodiment.

[0059] Reduction of the number of components and assembly processes can be achieved to greatly improve assembly efficiency because the illuminating optical system 60 is produced per each block and the entire unit is assembled simply by adhering one to the other consistently. Therefore, reduction of production cost is achieved as described in said first embodiment.

[0060] In the above described first embodiment, although the illuminating optical system 32 is divided into the block having a single function to disperse three colors of light and the block having a single function to reflect each of dispersed colors of light toward the projection optical system 33, both functions, namely dispersion and reflection, may be provided in a single block as shown in FIG. 4. Here, an illuminating optical system 81 is divided into a first block 82, a second block 83, a third block 84, and a forth block 85.

[0061] The first block 82 is provided with an input surface 82A for the white light from the light source, a red reflecting surface 82B for reflecting the red color of light, and a blue reflecting surface 82C for reflecting the blue color of light.

[0062] The second block 83 is provided with a blue reflecting surface 83A that is integral with the blue reflecting surface 82C of said first block 82, a red reflecting surface 83B that reflects the red color of light, and a dichroic mirror 83C that outputs the inputted red color of light to the projection optical system 33.

[0063] The third block 84 is provided with a red reflecting surface 84A that is integral with the red reflecting surface 83B of said second block 83, a blue reflecting surface 84B that reflects the blue color of light, and a dichroic mirror 84C that outputs the inputted green color of light to the projection optical system 33.

[0064] The fourth block 85 is provided with a blue reflecting surface 85A that is integral with the blue reflecting surface 84B of said third block 84, a red reflecting surface 85B that is integral with the red reflecting surface 82B of said first block 82, and a dichroic mirror 85C that outputs the inputted blue color of light to the projection optical system 33.

[0065] This case is also expected to have the same action and effect as said first embodiment of the color image projecting device 31.

[0066] Although the illuminating optical system 60 is divided into three blocks, namely 66, 67, and 68, the illuminating optical system may comprise two blocks as shown in FIG. 5. That is to say, an illuminating optical system 91 may comprise a first block 92 and a second block 93. A first block 92 is formed integrally in one piece by the first block 66 and the third block 68 of the second embodiment. The second block 93 is the same as the second block 67 of the second embodiment.

[0067] This case is also expected to have the same action and effect as said first embodiment of the color image projecting device 31.

[0068] Although three reflecting surfaces for reflecting three colors of light toward the projection optical system are provided in each of said embodiments, when the input direction of the white light from the light source is directed toward the projection optical system 33 as shown in FIG. 6 and FIG. 7, two reflecting surfaces may be provided.

[0069] In FIG. 6, the illuminating optical system comprises a first block 101 and a second block 102. The first block 101 comprises a dichroic mirror 103 that reflects the red color of light and a reflecting surface 104 that reflects red color of light reflected off the dichroic mirror 103 toward the projection optical system 33. The second block comprises a dichroic mirror 105 that reflects the blue color of light and a reflecting surface 106 that reflects blue color of light reflected off the dichroic mirror 105 toward the projection optical system. The green color of light is transmitted through the dichroic mirrors 103 and 105 to propagate rectilinearly.

[0070] In FIG. 7, the illuminating optical system comprises a single block 111. The single block 111 is provided with a dichroic mirror 112 that reflects red color of light, a reflecting surface 113 that reflects red color of light reflected off the dichroic mirror 112 toward the projection optical system 33, a dichroic mirror 114 that reflects blue color of light, and a reflecting surface 115 that reflects the blue color of light reflected off the dichroic mirror 114 toward the projection optical system. The green color of light is transmitted through the dichroic mirrors 112 and 114 to propagate rectilinearly.

[0071] This case is also expected to have the same action and effect as each of said embodiments. 

What is claimed is:
 1. An illuminating optical system comprising: a light source that emits white light including red, green, and blue colors; and a dividing-spectra block that is provided facing said light source; said dividing-spectra block having at least; a first reflecting surface that is provided on an optical path from said light source and reflects one of three colors of light while transmitting remaining colors of light; a first reflecting surface for extraction that extracts light which is reflected off said first reflecting surface by reflection in a predetermined direction; a second reflecting surface that is provided on said optical path from said light source and reflects another one of said three colors of light while transmitting a remaining color of light; and a second reflecting surface for extraction that extracts light which is reflected off said second reflecting surface by reflection in a predetermined direction.
 2. The illuminating optical system according to claim 1 wherein said each reflecting surface of said block comprises a dichroic mirror which reflects or transmits only any one color of light of said red, green, and blue colors.
 3. The illuminating optical system according to claim 1 wherein said block is formed of transparent plastic.
 4. An illuminating optical system comprising: a light source that emits white light including red, green, and blue colors; a first block that has at least a reflecting surface which reflects or transmits one of three colors of light from said light source in a predetermined direction while transmitting or reflecting remaining colors of light; and a second block that is provided in contact with said first block and has at least a reflecting surface which reflects or transmits one of two colors of light transmitted through or reflected off said reflecting surface in a predetermined direction while transmitting or reflecting a remaining color of light.
 5. The illuminating optical system according to claim 4 wherein said each reflecting surface of said each block comprises a dichroic mirror which reflects or transmits only any one color of light of said red, green, and blue colors of light.
 6. The illuminating optical system according to claim 4 wherein said each block is formed of transparent plastic.
 7. The illuminating optical system according to claim 4 wherein a third block that is provided in contact with said second block and has a reflecting surface which reflects light transmitted through or reflected off said reflecting surface of said second block in a predetermined direction is included.
 8. The illuminating optical system according to claim 7 wherein said each reflecting surface of said each block comprises a dichroic mirror which reflects or transmits only any one color of light of said red, green, and blue colors.
 9. The illuminating optical system according to claim 7 wherein said each block is formed of transparent plastic.
 10. An illuminating optical system comprising: a light source that emits white light including red, green and blue colors; a dividing-spectra block wherein a first reflecting surface that reflects one of three colors of light from said light source while transmitting remaining colors of light and a second reflecting surface that reflects another color while transmitting a remaining color of light are provided on an identical optical path in order to disperse said three colors of light in three directions; a red block that is provided in contact with a surface of said dividing-spectra block from which a red color of light is outputted and has a reflecting surface for extraction which extracts said red color of light by reflection in a predetermined direction; a green block that is provided in contact with a surface of said dividing-spectra block from which a green color of light is outputted and has a reflecting surface for extraction which extracts said green color of light by reflection in a predetermined direction; and a blue block that is provided in contact with a surface of said dividing-spectra block from which a blue color of light is outputted and has a reflecting surface for extraction which extracts said blue color of light by reflection in a predetermined direction.
 11. The illuminating optical system according to claim 10 wherein said each reflecting surface of said each block comprises a dichroic mirror which reflects or transmits only any one color of light of said red, green, and blue colors.
 12. The illuminating optical system according to claim 10 wherein said each block is formed of transparent plastic.
 13. A color image projecting device comprising: an illuminating optical system that outputs red, green, and blue colors of light by separating white light; and a projection optical system that forms a color projection image by three colors of light from said illuminating optical system; said illuminating optical system having a light source that emits said white light including said red, green, and blue colors and a dividing-spectra block that is provided facing said light source; said dividing-spectra block having; a first reflecting surface that is provided on an optical path from said light source and reflects at least one of three colors of light while transmitting remaining colors of light; a first reflecting surface for extraction that extracts light which is reflected off said first reflecting surface by reflection in a predetermined direction; a second reflecting surface that is provided on said optical path from said light source and reflects another one of said three colors of light while transmitting a remaining color of light; and a second reflecting surface for extraction that extracts light which is reflected off said second reflecting surface by reflection in a predetermined direction.
 14. A color image projecting device comprising: an illuminating optical system that outputs red, green, and blue colors of light by separating white light; and a projection optical system that forms a color projection image by three colors of light from said illuminating optical system; said illuminating optical system having; a light source that emits said white light including said red, green, and blue colors; a first block that has at least a reflecting surface which reflects or transmits one of said three colors of light from said light source in a predetermined direction while transmitting or reflecting remaining colors of light; and a second block that is provided in contact with said first block and has at least a reflecting surface which reflects or transmits one of two colors of light transmitted through or reflected off said reflecting surface in a predetermined direction while transmitting or reflecting a remaining color of light.
 15. A color image projecting device comprising: an illuminating optical system that outputs red, green, and blue colors of light by separating white light; and a projection optical system that forms a color projection image by three colors of light from said illuminating optical system; said illuminating optical system having; a light source that emits said white light including said red, green, and blue colors; a first block that has at least a reflecting surface which reflects or transmits one of said three colors of light from said light source in a predetermined direction while transmitting or reflecting remaining colors of light; a second block that is provided in contact with said first block and has at least a reflecting surface which reflects or transmits one of two colors of light transmitted through or reflected off said reflecting surface in a predetermined direction while transmitting or reflecting a remaining color of light; and a third block that is provided in contact with said second block and has a reflecting surface which reflects light transmitted through or reflected off said reflecting surface of said second block in a predetermined direction.
 16. A color image projecting device comprising: an illuminating optical system that outputs red, green, and blue colors of light by separating white light; and a projection optical system that forms a color projection image by three colors of light from said illuminating optical system; said illuminating optical system having; a light source that emits said white light including said red, green, and blue colors; a dividing-spectra block wherein a first reflecting surface that reflects one of three colors of light from said light source while transmitting remaining colors of light and a second reflecting surface that reflects another color while transmitting a remaining color of light are provided on an identical optical path in order to disperse said three colors of light in three directions; a red block that is provided in contact with a surface of said dividing-spectra block from which a red color of light is outputted and has a reflecting surface for extraction which extracts said red color of light by reflection in a predetermined direction; a green block that is provided in contact with a surface of said dividing-spectra block from which a green color of light is outputted and has a reflecting surface for extraction which extracts said green color of light by reflection in a predetermined direction; and a blue block that is provided in contact with a surface of said dividing-spectra block from which a blue color of light is outputted and has a reflecting surface for extraction which extracts said blue color of light by reflection in a predetermined direction. 